The present invention relates to display devices and, in particular, to display devices comprising plural display elements.
The standard for conventional displays is the cathode ray tube (xe2x80x9cCRTxe2x80x9d) display such as is employed in television receivers, computer displays, information displays such as for airport and train station travel information and the like. CRTs have the desirable characteristics of a clear, bright display, even when viewed from a position off to the side, i.e. off its central axis, coupled with reliability and stability, all at low cost. As a result of the structures and dimensions of the deflection arrangements required to scan the electron beam of a CRT over its phosphor-coated faceplate, the depth of a CRT is typically about as great as the diagonal of the display faceplate. While this is acceptable for moderate screen sizes, for example, up to about 35 inch diagonal dimension, the depth becomes excessive for larger screen sizes. Even CRTs having screen diagonals of 25 to 35 inches may be too deep for convenient use in smaller rooms. Larger conventional optical projection displays have images in the 35- to 45-inch diagonal range, but also have substantial depth and do not have the image brightness, especially from off-central viewing positions, and stability of CRTs.
One conventional solution is to create a larger display by placing several smaller displays side by side. For example, twelve television sets or other CRT displays DD1 through DD12 could be stacked up three high by four wide to create a large screen display 10 in which one-twelfth of the image is displayed on each television set DD1-DD12, as illustrated in FIG. 1. However, because the CRT in each television set both does not display an image all the way to the edges of its faceplate, and because the glass envelope of the faceplate is not exactly rectangular, there will necessarily be horizontal and vertical spaces 11, 12, 13, 14, 15 between the edges of the respective CRTs where no image is present. These spaces are often referred to as xe2x80x9cseamsxe2x80x9d or xe2x80x9cgaps.xe2x80x9d While designers of large displays have tried to minimize the inactive edge areas of display modules comprising such display, and thereby minimize these seams or gaps, they have not been able to eliminate them, and so visible and annoying gaps remain in the images displayed by such devices.
Even with rear-projection systems, the mullions of their respective diffuser panels leave a visible image-less seam. Front-projection systems have eliminated the mullion problem, but have great difficulty in projecting a true combined image in the seam areas which are usually sought to be minimized by involved and time-consuming complex set up and alignment procedures. In any of the foregoing arrangements, differences in resolution, geometry, brightness, intensity, and color between the portions of the combined image, or sub-images, produced by the various display units making up a larger display can produce noticeable variations in the displayed image. Such effects are well known and easily seen, for example, in the jumbo television displays often used at sporting arenas, concerts and outdoor events.
In addition to the desire for large image size, there is also a need for high image resolution along with large size. This need is evident, for example, regarding high-definition television (HDTV) systems and industrial and military displays. For high-definition displays of maps and charts, or of surveillance images, displays having resolutions of 100 dots per inch over a 30xc3x9740 inch display are desired. Such images include 12 mega-pixels of displayed information. Unfortunately, displays having such capabilities do not exist with conventional technologies. It is further desirable that such large display devices be easily transported and set up, and that they be available at a reasonable cost.
Accordingly, there is a need for a display system that is capable of providing high resolution and a virtually seamless image even over a relatively large display area.
To this end, the present invention comprises at least two image generators generating adjacent portions of an image on a screen, wherein the adjacent portions of the image overlap; and an image processor providing image data to the image generators including pixel data representative of particular pixels in the overlap that are adjusted so that the respective pixels generated therein by the two image generators combine to form the particular pixels.
According to another aspect of the present invention, a method of forming a substantially seamless pixelated image comprises:
forming two contiguous pixelated sub-images having a region of overlap at their common edge;
determining the value of particular pixels in the region of overlap;
determining a correction function for changing the determined value of the particular pixels in the overlap region to a given value; and
applying the correction function to respective pixel values of each of the pixelated sub-images for each of the particular pixels in the overlap region.